#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>
#include <math.h>

const theta = -30;
const PI = 3.1415;

void draw(){

    glBegin(GL_LINE_LOOP);

        glVertex2d(1,1);
        glVertex2d(2,2);
        glVertex2d(1,3);
        glVertex2d(0,2);

    glEnd();

}


void display(void){

    double c,s;

    c = cos(PI*theta/180.0);
    s = sin(PI*theta/180.0);

    // Vai para origem
    double matrix_origin[16]={1.0,0,0,0,
                        0,1.0,0,0,
                        0,0,1.0,0,
                        -1.0,-1.0,0,1};

    // pos inicial
    double matrix_init[16]={1.0,0,0,0,
                        0,1.0,0,0,
                        0,0,1.0,0,
                        1.0,1.0,0,1};
    // rotaciona em z
    double matrixRZ[16]={c,s,0,0,
                        -s,c,0,0,
                        0,0,1,0,
                        0,0,0,1};


   glClearColor (1.0, 1.0, 1.0, 0.0);
   glClear (GL_COLOR_BUFFER_BIT);
   glColor3f (0.0, 0.0, 0.0);

   glLoadIdentity ();
   draw();

   glPushMatrix();
   glMultMatrixd(matrix_init);
   glMultMatrixd(matrixRZ);
   glMultMatrixd(matrix_origin);
   draw();
   glPopMatrix();

   glFlush ();
}

void reshape(int w, int h){

    glViewport (0, 0, (GLsizei) w, (GLsizei) h);
    glMatrixMode (GL_PROJECTION);
    glLoadIdentity ();
    //glFrustum (-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);
    gluOrtho2D (-10.0, 10.0, -10.0, 10.0);
    glMatrixMode (GL_MODELVIEW);
}

int main(int argc, char** argv){

    glutInit(&argc, argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);

    glutInitWindowSize (500,440);
    glutInitWindowPosition (10, 10);
    glutCreateWindow (argv[0]);

    glutDisplayFunc(display);
    glutReshapeFunc(reshape);

    glutMainLoop();
    return 0;
}